Util.Benchmark 

Benchmark is a basic comparison testing tool

JVM technology makes it difficult to get absolute performance data

Benchmark allows to run several targets side by side, comparing their performance against each other

Let's benchmark 'append' performance for List, Vector and Buffer

import scala.collection.mutable.Buffer

scalqa.Util.Benchmark(
  ("List  ", () => { var v: List[Int]   = Nil;          for (i <- 1 to 1000) v = i :: v; v.size }),
  ("Vector", () => { var v: Vector[Int] = Vector.empty; for (i <- 1 to 1000) v = v :+ i; v.size }),
  ("Buffer", () => { val v: Buffer[Int] = Buffer.empty; for (i <- 1 to 1000) v += i;     v.size }))

// Output

Final Result.  Total Duration ~ 12 sec
--- ------ ------- --- ------ --- -----------------
Num Name   Ops/Sec %   Memory %   Control Value Avg
--- ------ ------- --- ------ --- -----------------
1   List   60.9k   53  38.0k  17  1000
2   Vector 13.5k   11  217.1k 100 1000
3   Buffer 113.2k  100 20.4k  9   1000
--- ------ ------- --- ------ --- -----------------

The results present three values:

• 'Ops/Sec' is the number of times the target executed per second
• 'Memory' is the average memory increase for one execution
• 'Control Value Avg' is the average of target returns for validity check. Generally, all targets should arrive to the same value in different ways

Note. Absolute values are less informative than following percentages of the largest value

From the above example, the following conclusions can be made:

• List is twice and Vector is ten times slower than Buffer
• Vector is seriously heavier on memory